Chordoma Detected on F-18 FDG PET

Characterization of sacral chordoma and differential diagnosis from other sacral malignancy using [18F]FDG PET/CT

2-Deoxy-2-[18F]fluoro-D-glucose ([18F]FDG) positron emission tomography (PET)/computed tomography (CT) is known to be a helpful imaging modality for sacral chordoma, but its detailed characteristics have not been fully described. The purpose of our study was to identify the [18F]FDG PET/CT imaging characteristics of sacral chordoma and compare them with other sacral malignancy. This retrospective study included patients who underwent [18F]FDG PET/CT because of a mass involving the sacrum. Investigated visual findings included visual score and distribution, and semiquantitative parameters measured included standardized uptake values (SUVmax, SUVpeak, SUVmean), tumor-to-liver ratio (TLR), metabolic tumor volume (MTV), total lesion glycolysis (TLG), and tumor size. Comparison studies and receiver operating characteristics (ROC) curve analysis were performed to differentiate between sacral chordoma and other sacral malignancy. Ten patients with sacral chordoma were finally included (M:F = 6:4, median age = 67 yr). On [18F]FDG PET/CT, sacral chordomas presented as a mass with minimal-moderate uptake with a usually heterogenous distribution. Compared with 12 patients with other sacral malignancies (M:F = 4:8, median age 42 yr), sacral chordoma showed a significantly lower TLR (median value 2.1 vs 6.3, P = .021). In ROC curve analysis, TLR showed the largest area under the curve (AUC) of 0.79 (cutoff ≤ 4.0; sensitivity 100.0%, specificity 58.3%; P = .004), and SUVmax showed the second largest AUC of 0.73 (cutoff ≤ 6.9; sensitivity 80.0%, specificity 66.7%; P = .034). [18F]FDG PET/CT of sacral chordoma showed minimal-moderate uptake. The TLR of [18F]FDG PET/CT was significantly lower than that of other sacral malignancy and was the most useful parameter for differentiating sacral chordoma, with the largest AUC. SUVmax could be another helpful semiquantitative parameter.

Chordoma: 18F-FDG PET/CT and MRI imaging features

OBJECTIVE

Examine the ¹⁸F-FDG PET/CT and MRI imaging characteristics of chordoma.

MATERIALS AND METHODS

Biopsy-proven chordoma with a pre-therapy ¹⁸F-FDG PET/CT from 2001 through 2019 in patients > 18 years old were retrospectively reviewed. Multiple PET/CT and MRI imaging parameters were assessed.

RESULTS

A total of 23 chordoma patients were included (16 M, 7 F; average age of 60.1 ± 13.0 years) with comparative MRI available in 22 cases. This included 13 sacrococcygeal, 9 mobile spine, and one clival lesions. On ¹⁸F-FDG PET/CT, chordomas demonstrated an average SUVmax of 5.8 ± 3.7, average metabolic tumor volume (MTV) of 160.2 ± 263.8 cm³, and average total lesion glycolysis (TLG) of 542.6 ± 1210 g. All demonstrated heterogeneous FDG activity. On MRI, chordomas were predominantly T2 hyperintense (22/22) and T1 isointense (18/22), contained small foci of T1 hyperintensity (17/22), and demonstrated heterogeneous enhancement (14/20). There were no statistically significant associations found between ¹⁸F-FDG PET/CT and MRI imaging features. There was no relationship of SUVmax (p = 0.53), MTV (p = 0.47), TLG (p = 0.48), maximal dimension (p = 0.92), or volume (p = 0.45) to the development of recurrent or metastatic disease which occurred in 6/22 patients over a mean follow-up duration of 4.1 ± 2.0 years.

CONCLUSION

On ¹⁸F-FDG PET/CT imaging, chordomas demonstrate moderate, heterogeneous FDG uptake. Predominant T2 hyperintensity and small foci of internal increased T1 signal are common on MRI. The inherent FDG avidity of chordomas suggests that ¹⁸F-FDG PET/CT may be a useful modality for staging, evaluating treatment response, and assessing for recurrent or metastatic disease.

Role of diffusion-weighted imaging in monitoring treatment response following high-intensity focused ultrasound ablation of recurrent sacral chordoma

Chordoma is the most common malignant tumor of the sacrum and is associated with significant neurologic morbidity. Local recurrence is very common, and the long-term prognosis is poor. High-intensity focused ultrasound (HIFU) is a noninvasive and nonionising ablative therapy that has been successful in treating other tumor types and is being evaluated as a new therapy for sacral chordoma. Contrast-enhanced magnetic resonance imaging is typically used to evaluate tumor perfusion following HIFU; however, its utility is limited in poorly perfused tumors. Diffusion-weighted imaging (DWI) provides tissue contrast based on differences in the diffusion of extracellular water without using gadolinium-based contrast agents. We present novel DWI findings following a planned partial HIFU ablation of a large sacral chordoma which had recurred after radiotherapy. Following HIFU, the treated tumor volume demonstrated loss of restriction on DWI correlating with photopenia on positron emission tomography. This suggests successful ablation and tumor necrosis. This novel finding may provide guidance for sequence selection when evaluating HIFU therapy for sacral chordoma and other tumor types for which contrast-enhanced magnetic resonance imaging may have limited utility.

Clival chordoma with drop metastases

Chordoma is a rare midline malignant tumor arising from embryonic remnants of the primitive notochord. The base of the skull is the second most common site of disease after the sacrococcygeal region. Intracranial chordoma constitutes about 30-35% of chordoma cases. Metastasis from chordoma is uncommon but if occurs, it tends to spread to the lungs. Cerebrospinal fluid seeding or drop metastasis is very rare. Here we describe a case of a clival chordoma with drop metastases.

Parosteal extra-axial chordoma of the second metacarpal bone: a case report with literature review

Extra-axial chordoma is a chordoma that occurs in non-axial locations. It is a very rare tumor, with 20 cases reported to date; 14 in bone and six in soft tissue. Of the 14 skeletal extra-axial chordomas, ten were intramedullary and four were intracortical. We report the first case of parosteal extra-axial chordoma arising in the second metacarpal bone, expressing brachyury on immunohistochemical analysis, and describe the pathologic and radiologic findings. We suggest that extra-axial chordoma can occur in parosteal bone lesions or the hand, without features of bone distribution or bone-specific sites.

Humeral metastasis of sacrococcygeal chordoma detected by fluorine-18 fluorodeoxyglucose positron emission tomography-computed tomography: A case report

Chordomas are rare, slow-growing, locally aggressive bone tumors arising from embryonic remnants of the notochord. Distant metastases most commonly involve the lung, liver, axial skeleton, skin, and lymph nodes. Humeral metastases are extremely rare. We report the case of a recurrent chordoma with humeral metastasis, complicated with pathologic fracture. Fluorine-18 fluorodeoxyglucose positron emission tomography-computed tomography revealed multiple hypermetabolic skeletal lesions, corresponding to the symptoms. Our report suggests that positron emission tomography-computed tomography is useful for evaluation of recurrence and distant metastases of chordomas.

68Ga-DOTA-TATE PET/CT for Molecular Imaging of Somatostatin Receptor Expression in Metastasizing Chordoma: Comparison With 18F-FDG

Chordoma is a rare slow-growing neoplasm of neuroectodermal origin, which frequently recurs after removal and has the potential to metastasize. We present the case of a 53-year-old man with metastasizing chordoma who underwent F-FDG and Ga-DOTA-TATE PET/CT for restaging of disease and for evaluation of targeted radionuclide therapy potential. On both F-FDG and Ga-DOTA-TATE PET scans, increased tracer accumulation was observed in chordoma metastases. Besides the increased glucose metabolism in chordoma, this case highlights the potential of Ga-DOTA-TATE PET/CT for restaging of chordoma as well the option of targeted radionuclide therapy in this entity.

Positron emission tomography/computed tomography imaging of residual skull base chordoma before radiotherapy using fluoromisonidazole and fluorodeoxyglucose: potential consequences for dose painting

PURPOSE

To detect the presence of hypoxic tissue, which is known to increase the radioresistant phenotype, by its uptake of fluoromisonidazole (18F) (FMISO) using hybrid positron emission tomography/computed tomography (PET/CT) imaging, and to compare it with the glucose-avid tumor tissue imaged with fluorodeoxyglucose (18F) (FDG), in residual postsurgical skull base chordoma scheduled for radiotherapy.

PATIENTS AND METHODS

Seven patients with incompletely resected skull base chordomas were planned for high-dose radiotherapy (dose ≥70 Gy). All 7 patients underwent FDG and FMISO PET/CT. Images were analyzed qualitatively by visual examination and semiquantitatively by computing the ratio of the maximal standardized uptake value (SUVmax) of the tumor and cerebellum (T/C R), with delineation of lesions on conventional imaging.

RESULTS

Of the eight lesion sites imaged with FDG PET/CT, only one was visible, whereas seven of nine lesions were visible on FMISO PET/CT. The median SUVmax in the tumor area was 2.8 g/mL (minimum 2.1; maximum 3.5) for FDG and 0.83 g/mL (minimum 0.3; maximum 1.2) for FMISO. The T/C R values ranged between 0.30 and 0.63 for FDG (median, 0.41) and between 0.75 and 2.20 for FMISO (median,1.59). FMISO T/C R >1 in six lesions suggested the presence of hypoxic tissue. There was no correlation between FMISO and FDG uptake in individual chordomas (r = 0.18, p = 0.7).

CONCLUSION

FMISO PET/CT enables imaging of the hypoxic component in residual chordomas. In the future, it could help to better define boosted volumes for irradiation and to overcome the radioresistance of these lesions. No relationship was founded between hypoxia and glucose metabolism in these tumors after initial surgery.

Surgical removal of chondroma of the petrous apex resulting in hearing improvement--case report

An 18-year-old male presented with a chondroma in the petrous apex manifesting as major complaints of headaches and sensorineural hearing disturbance on the right. Head computed tomography and magnetic resonance imaging revealed a neoplastic lesion in the right petrous apex, which had bulged to compress the internal auditory meatus. Surgical removal improved his hearing with normalization of the postoperative air conduction threshold by reduction of the pressure of the internal auditory meatus, suggesting that the function of the cochlea was retained and the tumor was compressing the cochleal nerve at the level of the internal auditory meatus. Histological examination showed the tumor consisted of hyaline cartilage tissue without cellular atypia and the diagnosis was chondroma.

F-18 FDG PET/CT evaluation of sacrococcygeal chordoma

Chordoma is a rare malignant bone tumor derived from notochordal rests, and the most common site is the sacrococcygeal region. A 52-year-old woman presented with a sacrococcygeal chordoma detected on F-18 fluorodeoxyglucose (FDG) positron emission tomography (PET)/computed tomography (CT). The F-18 FDG PET/CT showed a large destructive mass that arose anteriorly in the sacrococcygeal region and heterogeneously increased FDG uptake within the mass was observed. After surgery, histology confirmed the presence of a sacrococcygeal chordoma. The physician should take chordoma into consideration if there is a large osteolytic mass with hypermetabolism in the sacral region on FDG PET/CT.